I would put money on the Lens' mega-IOS being better than the e-pm2's (I own one) most of the time.
With crummy apertures you are going to need it,
but now you have the opportunity to post a whole thread about your findings ...

I took out my E-PM2 with 12-32 on the weekend. I was shocked at how much CA the lens exhibited in the wide end of the range. Otherwise, a great portable combo if you didn't cash in on the GM1 deal a while back.